Use Polya’s four-step problem-solving strategy and the problem-solving procedures presented in this section to solve each. A diagonal of a polygon is a line segment that connects nonadjacent vertices...

Use Polya’s four-step problem-solving strategy and the problem-solving procedures presented in this section to solve each. A diagonal of a polygon is a line segment that connects nonadjacent vertices of the polygon. In the following polygons, a triangle has 3 sides and 0 diagonal, a quadrilateral has 4 sides and 2 diagonals, a pentagon has 5 sides and 5 diagonals, a hexagon has 6 sides and 9 diagonals. Predict the number of diagonals in a 12-sided polygon.